Wall Street is tumbling on fears the big U.S. companies that have feasted on the artificial-intelligence frenzy are under threat from a competitor in China.

Big Tech stocks took some of the heaviest losses, with Nvidia down 11.2%, and they dragged the Nasdaq composite down 2.7%. The Dow Jones Industrial Average, which has less of an emphasis on tech, was holding up better with a dip of 123 points,